Coated glass plate



c. GRAMBACH COATED GLASS PLATE June 24, 1930.-

Filed July 12. 1927 Patented June 24, 1930 urreo STATES CARL GRAMBACH, OF ZURICH, SWITZERLAND 'coe'rnn crass PLATE Application filed July 12, 1927, Serial No. 205,084, and in Germany July 23, 1926.

My invention relates to improvements in coated glass plates, such as silver-coated glass plates used in the manufacture of mirrors. In glass plates of this class the coating is provided with a protective layer consisting of lacquer or the like. The object of the improvements is to provide a coated glass plate in which the destruction of the coating caused by atmospheric influences and humidw ity deposited thereon and by expansion of the coating by heat is avoided, and with this object in view my invention consists in providing the glass plate at the coated side thereof with a bezeled margin extending from the coated face to the circumferential margin thereof, the coating of the face of the plate extending to the said bezeled margin, and the protective layer or the like extending on the bezeled margin. Preferably,

the bezeled margin is roughened by suitable means so that the protective layer firmly sticks thereto.

In order that my invention be clearly understood a silver-coated glass plate of the construction now in use and a silver-coated glass plate embodying my invention have been shown in the accompanying drawing, in which the same reference characters have been used in all the views to indicate corrego sponding parts. In said drawing,

Fig. 1' is a sectional elevation showing the bottom part of a silver-coated glass plate of the construction now in use, and

Fig. 2 is a similar sectional elevation showing my improved glass plate.

As appears from Fig. 1, a silver-coated glass plate as now manufactured consists of a plate 1, a silver-coating 2 applied to the 7 rear face of the glass plate, and a protective *9 layer 3 applied to the rear face of the silvercoating. As shown in Fig. 1, both coatings extend to the outer margin of the plate.

Thus humidity deposited on the rear face of the mirror will collect at the lower margin thereof where it tends to loosen the silvercoating from the glass. Thereby the mirror is liable to be spoiled. Further, by nonuniform expansion by heat of the protective layer 3 andthe silver-coating 2, the said silver-coating is made loose more particularly at its margin.

As appears from Fig. 2 my improved silver-coated glass plate consists of a plate l having at its rear side a bezeled margin 5, U

a silver-coating 6 applied to the plane part of the rear face of the glass up to the line of intersection of the plane rear face and the bezeled margin 5, and a protective layer 7 of lacquer or the like covering the rear face of the silver-coating and the bezeled margin 5 of the glass plate. Thus the protective layer sticks to the bezeled margin of the glass plate, and it encloses the silver-coating 6 not only at the rear face thereof, but also at the margin thereof. Preferably, the bezeled margin 5 is made rough by suitable means, so that the protective layer firmly sticks thereto.

lit appears therefore that the silver-coating is entirely protected against atmospheric influences. Any humidity deposited on the rear face of the mirror and flowing downwardly thereon is collected at the lower margin of the bezeled portion 5 where it has no access to the silver-coating, and it does not pass between the protective layer 5 and the glass plate, the said protective layer being firmly united with the glass plate. If by mechanical influences the protective layer of the bezeled margin 5 is injured, the silvercoating is not exposed, because it extends only to a part away from the outer margin of the glass plate, where it is not subjected to mechanical injury. Further, the protective layer sticking to the bezeled margin 5 prevents loosening of the silver-coating from the glass plate in case of nonuniform expansion by heat of the coating and the layer.

In describing the invention reference has been made to silver-coated glass plates used in the manufacture of mirrors, but I wish it to be understood that my invention is not limited to such use and that it also applies to glass plates having aooating of differentcharacter.

I claim: Y

1. A glass body comprising a body having a rear face and a bezeled marginal edge bounding said rear face, a coating covering the rear face up to the line of intersection of said rear face and said bezeled marginal edge, and a protective layer covering the outer surface of said coating and extending beyond the latter into adhering contact with the bezeled marginal edge.

27 A glass plate comprising a body having a plane rear face and a bezeled marginal edge having a roughened surface bounding said plane rear face, a metallic coating covering the plane rear face up to the line of intel-section of said plane rear face and said bczeled marginal edge, and a protective layer covering the outer surface of said coatlng and extending beyond the latter to and covering the roughened surface of said bezeled marginal edge.

In testimony whereof, I hereunto affix my signature.

CARL GRAMBACH. 

